I think you're misunderstanding what I'm saying. I'm not saying thats mods/admins shouldn't have the ability to ban you from their community. Temporarily or permanently.
I'm saying that, to take your example, you get into a heated debate over a comic book. And the mod or admin there bans you. Not from their community, not from their instance, but from ALL of Lemmy.
That's what I think shouldn't happen. I don't think ANY admin or mod should be able to ban you from the whole platform. They can certainly ban you from their space, but not from all spaces at once.